Asphalt is primarily used for paving, with secondary uses being roofing products and specialty applications. Asphalt is by nature a thermoplastic material, and is relatively inexpensive compared with most other thermoplastics. Because of its thermoplastic nature, asphalt uses are limited to applications where the asphalt is not exposed to excessive heat, or where creep and distortion are not of concern. It would be advantageous if asphalt could be used in thermoset applications, such as heat-curable coatings or molding compositions.
Numerous products known in the art combine asphalt with other materials. These combinations include reinforcing asphalt with, for example glass fibers; blending other materials, such as synthetic rubber, with asphalt; and chemically modifying asphalt with such materials as polymers. Blending additives with asphalt and chemically modifying asphalts have produced many products with beneficial properties. One problem with the blending and chemical modification processes is that the desired end result properties often require significant amounts of expensive modifiers, such as synthetic polymers. It would be advantageous to be able to obtain desirable properties of modified asphalt products with a small amount of modifiers, such as 30 percent or less by weight of the combined asphalt and modifier composition.
Another problem with asphalt modifiers is that asphalt contains a wide range of chemical functionalities, so that developing a cross-linked network that does not allow one component to bleed out or separate is very difficult.
Accordingly, it would be advantageous if asphalt, a relatively inexpensive thermoplastic material could be converted into a thermosetting material, particularly if the process for converting asphalt into a thermosetting product required a minimum of expensive additive materials.